<?php

/**
 * @file cache.inc
 *
 * Functions to load Views' data so that it knows what is available to
 * build queries from.
 */

/**
 * Load views files on behalf of modules.
 */
function _views_include_handlers() {
    views_module_include('views.inc');
}

/**
 * Load default views files on behalf of modules.
 */
function _views_include_default_views() {
    views_module_include('views_default.inc');
}

/**
 * Fetch Views' data from the cache
 */
function _views_fetch_data($table = NULL) {
    static $cache = NULL;
    if (!isset($cache)) {
        $start = views_microtime();
        // NOTE: This happens whether we retrieve them from cache or otherwise.
        views_include_handlers();

        $data = views_cache_get('views_data', TRUE);
        if (!empty($data->data)) {
            $cache = $data->data;
        }

        if (empty($cache)) {
            $cache = module_invoke_all('views_data');
            foreach (module_implements('views_data_alter') as $module) {
                $function = $module . '_views_data_alter';
                $function($cache);
            }

            views_cache_set('views_data', $cache, TRUE);
        }

        vpr('Views data build time: ' . (views_microtime() - $start) * 1000 . ' ms');
    }

    if (!$table) {
        return $cache;
    }
    if (isset($cache[$table])) {
        return $cache[$table];
    }

    // Return an empty array if there is no match.
    return array();
}

/**
 * Fetch the plugin data from cache.
 */
function _views_fetch_plugin_data($type = NULL, $plugin = NULL) {
    static $cache = NULL;
    if (!isset($cache)) {
        $start = views_microtime();
        views_include_handlers();

        $cache = views_discover_plugins();

        vpr('Views plugins build time: ' . (views_microtime() - $start) * 1000 . ' ms');
    }

    if (!$type && !$plugin) {
        return $cache;
    } else if (!$plugin) {
        // Not in the if above so the else below won't run
        if (isset($cache[$type])) {
            return $cache[$type];
        }
    } else if (isset($cache[$type][$plugin])) {
        return $cache[$type][$plugin];
    }

    // Return an empty array if there is no match.
    return array();
}

/**
 * Scan all modules for default views and rebuild the default views cache.
 *
 * @return An associative array of all known default views.
 */
function _views_discover_default_views() {
    static $cache = NULL;

    if (!isset($cache)) {
        $index = views_cache_get('views_default_views_index', TRUE);

        // Retrieve each cached default view
        if (isset($index->data) && is_array($index->data)) {
            $cache = array();
            foreach ($index->data as $view_name) {
                $data = views_cache_get('views_default:' . $view_name, TRUE);
                if (isset($data->data) && is_object($data->data)) {
                    $cache[$view_name] = $data->data;
                }
            }
        }
        // If missing index, rebuild the cache
        else {
            views_include_default_views();
            $cache = array();

            foreach (module_implements('views_default_views') as $module) {
                $results = call_user_func($module . "_views_default_views");
                if (!empty($results) && is_array($results)) {
                    foreach ($results as $name => $view) {
                        // Only views with a sufficiently high api version are eligible.
                        if (!empty($view->api_version) && $view->api_version >= 2) {
                            // Do not cache dead handlers.
                            $view->destroy();
                            if (!isset($cache[$name])) {
                                $cache[$name] = $view;
                            } else {
                                watchdog('view', "View name '@name' is already taken", array('@name' => $name), WATCHDOG_ERROR);
                            }
                        }
                    }
                }
            }

            // Allow modules to modify default views before they are cached.
            drupal_alter('views_default_views', $cache);

            // Cache the index
            $index = array_keys($cache);
            views_cache_set('views_default_views_index', $index, TRUE);

            // Cache each view
            foreach ($cache as $name => $view) {
                views_cache_set('views_default:' . $name, $view, TRUE);
            }
        }
    }

    return $cache;
}

/**
 * Set a cached item in the views cache.
 *
 * This is just a convenience wrapper around cache_set().
 *
 * @param $cid
 *   The cache ID of the data to store.
 * @param $data
 *   The data to store in the cache. Complex data types will be automatically serialized before insertion.
 *   Strings will be stored as plain text and not serialized.
 * @param $use_language
 *   If TRUE, the data will be cached specific to the currently active language.
 */
function views_cache_set($cid, $data, $use_language = FALSE) {
    global $language;

    if (variable_get('views_skip_cache', FALSE)) {
        return;
    }
    if ($use_language) {
        $cid .= ':' . $language->language;
    }

    cache_set($cid, $data, 'cache_views');
}

/**
 * Return data from the persistent views cache.
 *
 * This is just a convenience wrapper around cache_get().
 *
 * @param $cid
 *   The cache ID of the data to retrieve.
 * @param $use_language
 *   If TRUE, the data will be requested specific to the currently active language.
 */
function views_cache_get($cid, $use_language = FALSE) {
    global $language;

    if (variable_get('views_skip_cache', FALSE)) {
        return 0;
    }
    if ($use_language) {
        $cid .= ':' . $language->language;
    }

    return cache_get($cid, 'cache_views');
}

/**
 * @defgroup views_object_cache Non-volatile cache storage
 * @{
 * The non-volatile object cache is used to store an object while it is
 * being edited, so that we don't have to save until we're completely
 * done. The cache should be 'cleaned' on a regular basis, meaning to
 * remove old objects from the cache, but otherwise the data in this
 * cache must remain stable, as it includes unsaved changes.
 */

/**
 * Get an object from the non-volatile Views cache.
 *
 * This function caches in memory as well, so that multiple calls to this
 * will not result in multiple database reads.
 *
 * @param $obj
 *   A 32 character or less string to define what kind of object is being
 *   stored; primarily this is used to prevent collisions.
 * @param $name
 *   The name of the view (or other object) being stored.
 * @param $skip_cache
 *   Skip the memory cache, meaning this must be read from the db again.
 *
 * @return
 *   The data that was cached.
 */
function views_object_cache_get($obj, $name, $skip_cache = FALSE) {
    static $cache = array();
    $key = "$obj:$name";
    if ($skip_cache) {
        unset($cache[$key]);
    }

    if (!array_key_exists($key, $cache)) {
        $data = db_fetch_object(db_query("SELECT * FROM {views_object_cache} WHERE sid = '%s' AND obj = '%s' AND name = '%s'", session_id(), $obj, $name));
        if ($data) {
            $cache[$key] = unserialize($data->data);
        }
    }
    return isset($cache[$key]) ? $cache[$key] : NULL;
}

/**
 * Store an object in the non-volatile Views cache.
 *
 * @param $obj
 *   A 32 character or less string to define what kind of object is being
 *   stored; primarily this is used to prevent collisions.
 * @param $name
 *   The name of the view (or other object) being stored.
 * @param $cache
 *   The object to be cached. This will be serialized prior to writing.
 */
function views_object_cache_set($obj, $name, $cache) {
    views_object_cache_clear($obj, $name);
    db_query("INSERT INTO {views_object_cache} (sid, obj, name, data, updated) VALUES ('%s', '%s', '%s', '%s', %d)", session_id(), $obj, $name, serialize($cache), time());
}

/**
 * Remove an object from the non-volatile Views cache
 *
 * @param $obj
 *   A 32 character or less string to define what kind of object is being
 *   stored; primarily this is used to prevent collisions.
 * @param $name
 *   The name of the view (or other object) being stored.
 */
function views_object_cache_clear($obj, $name) {
    db_query("DELETE FROM {views_object_cache} WHERE sid = '%s' AND obj = '%s' AND name = '%s'", session_id(), $obj, $name);
}

/**
 * Remove all objects in the object cache that are older than the
 * specified age.
 *
 * @param $age
 *   The minimum age of objects to remove, in seconds. For example, 86400 is
 *   one day. Defaults to 7 days.
 */
function views_object_cache_clean($age = NULL) {
    if (empty($age)) {
        $age = 86400 * 7; // 7 days
    }
    db_query("DELETE FROM {views_object_cache} WHERE updated < %d", time() - $age);
}

/**
 * @}
 */
